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b168057a | 1 | /* Copyright (C) 1995-2015 Free Software Foundation, Inc. |
84384f5b UD |
2 | This file is part of the GNU C Library. |
3 | Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, August 1995. | |
60478656 | 4 | |
84384f5b | 5 | The GNU C Library is free software; you can redistribute it and/or |
41bdb6e2 AJ |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
60478656 | 9 | |
84384f5b UD |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 13 | Lesser General Public License for more details. |
60478656 | 14 | |
41bdb6e2 | 15 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ | |
60478656 RM |
18 | |
19 | #include <errno.h> | |
20 | #include <stdlib.h> | |
1d8dc429 | 21 | #include <limits.h> |
d17c01f9 | 22 | #include <stdint.h> |
52e9a9d1 | 23 | #include <sys/types.h> |
60478656 | 24 | |
845dcb57 | 25 | /* Global state for non-reentrant functions. */ |
60478656 RM |
26 | struct drand48_data __libc_drand48_data; |
27 | ||
28 | ||
29 | int | |
30 | __drand48_iterate (xsubi, buffer) | |
31 | unsigned short int xsubi[3]; | |
32 | struct drand48_data *buffer; | |
33 | { | |
d17c01f9 UD |
34 | uint64_t X; |
35 | uint64_t result; | |
60478656 RM |
36 | |
37 | /* Initialize buffer, if not yet done. */ | |
a1ffb40e | 38 | if (__glibc_unlikely (!buffer->__init)) |
60478656 | 39 | { |
d17c01f9 UD |
40 | buffer->__a = 0x5deece66dull; |
41 | buffer->__c = 0xb; | |
42 | buffer->__init = 1; | |
60478656 RM |
43 | } |
44 | ||
45 | /* Do the real work. We choose a data type which contains at least | |
46 | 48 bits. Because we compute the modulus it does not care how | |
47 | many bits really are computed. */ | |
48 | ||
d17c01f9 | 49 | X = (uint64_t) xsubi[2] << 32 | (uint32_t) xsubi[1] << 16 | xsubi[0]; |
52e9a9d1 | 50 | |
d17c01f9 | 51 | result = X * buffer->__a + buffer->__c; |
52e9a9d1 | 52 | |
d17c01f9 UD |
53 | xsubi[0] = result & 0xffff; |
54 | xsubi[1] = (result >> 16) & 0xffff; | |
55 | xsubi[2] = (result >> 32) & 0xffff; | |
60478656 RM |
56 | |
57 | return 0; | |
58 | } |